Automatic air-spring.



R. LIEBAU.

AUTOMATIC MR SPRING. Arnlcmon msn I uw 5. m4.

Patented De.l18,191l7 .lllllll/llfllllllll H/s 'ATTORNEY '/N FACT e santas PATENT OFF Bierman LIEBAU, or ,NEW HAVEN, ooNNEc'rIcU'r, AssIeNon 'ro "rim wns'rmeHoUsE AIB SPRING COMPANY, A CORPORATION OF IIEINNSYLV'ANIA'.v

AUTOMTIC AIB-SPRING.

e vSpecification of Letters Patent. A Patented Dec.V 1S, 1917.

Application led May 5, 1914. Serial No. 886,447.`

To all whom 'it may concern: Y

Be it known that I, RICHARD LIEBAU, a citizen of the United States, and a resident of New Haven, in the county of New Haven, and State of Connecticut, have made a new Westinghouse on August 20, 1912.

-In the present case, as informer cases, the invention is embodied in a fluid cornpression device adapted for use as a compression spring and applicable in any rela-v tion where-two bodies ae so assoclated that resilient support is desirable; and the general object in view in this, as well as in the former cases, has been to embody the principle of resilient support byan elastic compression medium such a's air or gas in a commercially practical self-contained air-'f tight compression device adapted to serve f ferred to as an air spring),`means are provided for forcing Kair into the chamber of the' spring and alsov for automatically de' -termining the normal or operative relative positions Lof the relatively movable members of the spring irrespective of the load carried thereby.l Y It has'been found in using air springs on motor vehicles, such as automobiles, trucks,

etc., that it is desirable to have the air springs so adjusted that under normal condltions, when the vehicle is at rest, the air sprinI will stand in about mid position,

that is, that they will stand about onehalf l compressed in order that .substantially equal movement may be had above and below this mid or normal position.

- load surfaces is maintained by meansv of sliding joint, that under certain conditions a certain amount of air'from the oil-collecting chamber is pumped with the oil, thereby raising the pressure in the spring andchanging the normal running position to amore extended position than is desirable.

' In use on a motor vehicle, it is desirable to have the -airl springs so adjusted that the latforin of the vehicle, when the vehicle is :1t-reist, normally stands at a certain height from the ground, or, in other words, 1t is desired'to maintain the load platform at a certain height-v from the ground, so as-to allow the running gear of the vehicle to move up and down when the vehicle is in use.

In certain forms, as vbefore said, of the Y prior.' devices, it has been found thatfunder certain conditions so much air is pumped into the interior of the springs by means of the Aoil pumpthat the air pressure within the sprin s has been increased so that the load plat orm has been raised above its normal position.'

According to my present invention, I make use of the idea of pumping air into the air springs but provide means for,autom`ati cally determining the normal or operative positions of the-relatively movable members ofthe air springs irrespective of the load carried by the .load-carrying platform.

An object of this invention is to produce an air spring in Awhich means are provided for forcing air yinto the chamber of thespring and for providing means for automatically determining the normal or operative relative positions of the relatively movable members of the air 'springs irrespective of theload carried by the load-carrying platform of the vehicle with which they vare utilized. This, Las well as other objects-which will readily appear to those skilled in this art, I attain in the device described in the specification and illustrated in the `single sheet of drawings accompanying the same.

The drawing is a sectional elevation of an air spring embodying this invention. In the device,.the cushion chamber is made up of a cylinder 2 'provided' with a head 3 and which telescopeswithin a cylinder 4 having a bottom 5 formed in the nature of a crosshead. Secured to head 3 at 6 is an outer cylinder 7 which acts as a cover, or mud or dust guard and which is threaded within a spring guide member 8 at 9. r1`he guide member has a machined face 10 which may be bolted or otherwise secured to a corresponding face of a bracket, adapted to be rigidly bolted or riveted to the chassis or frameof the vehicle.

The crosshead 11 formed on the cylinder bottom 5 is adapted to be shackledby means of a shackle 12.to one end of the steel leaf spring 13 forming part of the running gear of the vehicle. '1`he air spring, it will be seen, is adapted to work in series with-the steel spring, and if an air spring is mo'unted leather packing and the packing is firmlyheld to said seat by means of a nut 17 threaded to the lower end of the plunger head. and which is provided with an upright extension 18 which clamps the cup-leather to its seat 16. A cone expander ring 19 is pressedagainst the inner depending lip of the cup-leather packing by means of a spring v 2O which lies between said expander andv the nut 17. l

A spring-backed leather wiper ring 21 bears against the inner surface of cylinder 4 and serves to retain oil or .other sealingV liquid in the chamber which contains the i cup-leather packing. Y

The depending liange of the cup-leather packing bears against the inner surface of cylinder 4 and the chamber containing the packing is in open communication with a reservoir formed by atubular element 22 threaded into plunger head 14 at 23. The reservoir is formed between cylinder 2 and element 22 and is adapted to be filledwith oil through a charging plug 24 threaded into head 3.

vA tubular member 25 forming a pump cylinder is threaded into bottom 5 and contains an air strainer 26 and a non-return ball check valve 27. A pump lplunger 28 carrying a non-return ball check valve 29 and provided with a bore 30 throughout its length is more or less loosely secured (to allow lateral adjustment) within a retainer 31 carried by head 3. This pump plunger Y is provided with an `outlet port 34, and the tubular member25 is provided with a regulating port 3,5. An air. charging valve 36 l Lamme is threaded into the top central portion of head 3 and a dust cap 37 covers the -valve and is threaded onto avboss formed onI the head 3. l

In use, the air spring will be'charged With oil or other sealing liquid through the charging plug 24 until the reservoir is lled. After the charging plug has been replaced air lwill be forced in through valve 36 until the relatively movable members of the spring stand `in their normal operative positions.

. Assume that the loady on the spring is su'ch that When not in action the relatively movable members will stand in the position shown in the drawing. During action, then, when the spring is compressed -and extended,

and will flow up through tubular member 25 through the opening 30 vin the plunger and out through outlet port 34 into the interior of the device, and this will take place until the spring has been distended while at rest. until the lower end of plunger 28 is 'above or in line with regulating outlet 35.

It will be seen that when the lower end of plunger 28 passes up above regulating outlet 35 no air will be drawn into the pump plunger through strainer 26. The pump i will only operate while the lowerend of tended so that the pump is rendered inoperative as an air pump'. If air leaks past the cup leather packing, which it cannot do` unair will be pumped in by means-of the pumpv through strainer 26 past ball check valve 27 til all of the oil from the reservoir has passed the cup-leather packing, the air pump f the tube 22 and the pump cylinder 25 forms a transfer passage for air during the compresslon and extension movements of the air spring. The oil which-leaks past the cupleather packingl will serve to keep the sliding surfaces properly lubricated. The reservoir is of such capacity that with the small leakage past thecup-leather packing, it will be suicientto supply the cup-leather packing with o'il for a considerable length of time. As the oil leaks out, the volumetric capacity for air in the spring will increase,

.but the nir pumpwiil automatically au. this increased s ace with air.

. In accor ance with the provisions of the patent statutes, I .have described the principle of operation of my lnvention, togetzhei-I with the device which I now consld'er to represent the best embodiment thereof, but

I desire to have it understood that the de-l vice shown is only illustrative and that the invention can beV carried out'in other ways.

What I Vclaim is:

1." A\ cushioning device comprising rela` tively movable members forming a 'chamber and having a sliding joint therebetween to .permit variations in the volumetric capacity of the chamber, meanslocated within the chamber and actuated by variations in the relative positions of said members for forcing liuid 'under pressure into said chamber,

and means for determining the relative positions of said'members, irrespective of the fluid pressure within said chamber, by rendering said iluid forcing means inoperative when said members assume ya determined position,"

2. A cushioning device comprising rela'- tively movable vmembers forming a chamber ofvariable volumetric capacity, a pump locatedwithin saidvchamberand actuated by the relative motion of said members for forcing air into said chamber and means independent of thepressure within said'chamber for rendering saidV pump inoperative when said members assume a determined relative position. e 3. A cushlonlng device, comprismg relatively movable members inclosing a chamber of variable volumetric capacity, a pump located within said chamber for receiving fluid from without the chamber and for forcing fiuid into the chamber, and means independent'of the pressure within the chamber for placing the interior of the plmp in direct communication with the chamber when said members assume a determined position.

4. A cushioning device for vehicles com i prising relatively movable members located etween the body and the runningygear and inclosing a chamber of variable volumetric capacity, means located within the lchamber and Iactuated by the relative motion of said members for forcing ui'd froman external source into saidchamb'er and means indesaid Huid forcing means. into said chamber.`

said chamber, and means independent of the fluid pressure within the chamber and conltrolled by th relative positions of said members for limitingthe degree of pressure pumped by said pump into said chamber.

6. A cushioning device for a vehicle, com- Y V prising' relatively movable members located.

between the bodyv and the running gear of the vehicle and inclosing a chamber of variable volumetric capacity, a pump operatingv upon the extension and compression movements of said members and comprising a piston and a coperating cylinder provided with an inlet valve receiving fluid from an exter-l nal sourcev and an outletv valve for delivering fluid to said chamber, and' a port in the pump cylinder controlled by the relative positions of said members for rendering said pump inoperative as a pumping agent when said members occupy a determined Cposition.

7. A cushioning device for a vehicle, comprising relatively :movable members located between the body Aand the running gear'of the vehicle and inclosing a chamber of variable volumetric capacity, a pump located within the chamber and comprising a plunger, operatively connected to one of 'said members, a cooperating piston operatlvely connected to the other member, an inlet.

nvalve ciontrolliu an inlet port formed in the cyllnder, and a `ischarge valve controlling a;

passage formed within the plunger: and communicating with said chamber, and a port located in said cylinder and controlled by said piston and adapted to establish direct communication betweenlthe chamber and the interior of thecylinder when the members assume a determined relative position.

8. A cushioningv device comprisin relatively movable members inclosing a chamber of variable volumetriccapacity, a pump located within said chamber, one mem- .ber of said pum I- being operatively con-vA nected to one'o said -relatively movable members and the other memberL of the pump Y being operatively connected to the other relatively movable member, and means dependent on-the relative positions of `said relatively movable members and independent of the pressure within'the chamber for limit- -ing the degree o f v1 pressure within the chamber by rendering said pump inoperative."

9. cushioning device, comprising two relatively movable members `inclosing, a

e .chamber of variable volumetric capacity, a

sliding jointbetween said members, a packing for said Joint, a reservoir located within s a-ld chamber` fortdeliveringsealing liquid -to said joint, a pump comprising a cylinder mounted on one member, ya pump plunger mounted on the other'nlember, and inlet and outlet valves, for drawing fluid from an erico two

ternall sourceand for forcing it into said chamber, and a port formed in said cylinder for establishing direct .communicatlon' bev tween the interior thereof and said chamber when said plunger is moved to a determined position.

10. A cushioning device comprising relatively movable members inclosing a chamber of Variable volumetric capacity, a pump located Within said chamber for forcing fluid from an external source into said chamber, and means independent of the pressure lWithin said chamber for limiting the degree of pressure pumped by said pump Without venting said chamber.

1l. A cushioning device comprising relatively movable members, inclosing a chamber of variable volumetric capacity, a plunger head carried by one of said members and located intermediate the ends of said chamber and having a passage formed therethrough for establishing free communication between the ends o-the chamber located on opposite sides thereof, a packing for the sliding joint between said members located on said head, a tubular element mounted onv said head, and forming an annular reservoir above said head for delivering liquid to said packing, and an air pump concentrically armaar@ ranged Within said chamber and extending through the passage in said head and having an inlet communicating with the atmosphere and an outlet communicating with said chamber.

12. In a cushion device comprising relatively movable members forming a chamber having a sliding joint therebetween, a plunger head carried by one of said members, apassage through said head establishing free communication between the top and bottom of said chamber on opposite sides thereof, an aii pump concentrically arranged within saidchamber having its inlet communicating with the atmosphere and its outlet with said chamber and means independent of the pressure Within said chamber for limiting the degree of pressure pumped by said pump Without venting said chamber. In testimony whereof I have hereunto sub` scribed my name this 29th day of April, 1914.

RICHARD LiEBAU.

Witnesses:

ARTHUR H. KINNEY, p GRACE E. FISHER. 

